Description
The IAX2 channel driver (chan_iax2) in Asterisk Open Source 1.0.x, 1.2.x before 1.2.28, and 1.4.x before 1.4.19.1; Business Edition A.x.x, B.x.x before B.2.5.2, and C.x.x before C.1.8.1; AsteriskNOW before 1.0.3; Appliance Developer Kit 0.x.x; and s800i before 1.1.0.3, when configured to allow unauthenticated calls, does not verify that an ACK response contains a call number matching the server's reply to a NEW message, which allows remote attackers to cause a denial of service (traffic amplification) via a spoofed ACK response that does not complete a 3-way handshake. NOTE: this issue exists because of an incomplete fix for CVE-2008-1923.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | asterisk | 1:1.4.19.1~dfsg-1 | — |
| Debian 4.0 | asterisk | 1:1.2.13~dfsg-2etch4 | DSA-1563-1 |
Advisories 1
- DSA-1563-1 asterisk - denial of service Debian Security (DSA / DLA) · Mar 9, 2026
References
- GLSA-200905-01 vendor-advisory
- 29927 third-party-advisory
- asterisk-iax2protocol-ack-dos(41966) vdb-entry
- 28901 vdb-entry
- 30010 third-party-advisory
- ADV-2008-1324 vdb-entry
- http://downloads.digium.com/pub/security/AST-2008-006.html
- http://bugs.digium.com/view.php?id=10078
- FEDORA-2008-3390 vendor-advisory
- 20080422 AST-2008-006 - 3-way handshake in IAX2 incomplete mailing-list
- http://www.altsci.com/concepts/page.php?s=asteri&p=2
- 30042 third-party-advisory
- DSA-1563 vendor-advisory
- 34982 third-party-advisory
- 1019918 vdb-entry
- FEDORA-2008-3365 vendor-advisory
- https://downloads.asterisk.org/pub/security/AST-2008-006.html
- https://github.com/xrg/asterisk-xrg/commit/51714a24347dc57f9a208a4a8af84115ef407b83
- https://github.com/jcollie/asterisk/commit/a8b180875b037b8da26f6a3bcc8e5e98b8c904d2
- https://github.com/xrg/asterisk-xrg/commit/10da3dab24e8ca08cf2c983f8d0206e383535b5a
- https://github.com/jcollie/asterisk/commit/771b3d8749b34b6eea4e03a2e514380da9582f90
- https://github.com/pruiz/asterisk/commit/e0ef9bd22810c6969a7f222eec04798f19a7e2d6
- https://github.com/jcollie/asterisk/commit/60de4fbbdf3ede49f158e23a9e3b679f2e519c1e
- https://github.com/mojolingo/asterisk/commit/20ac3662f137dbf7f42d5295590069a7d3b1166b
- https://github.com/silentindark/asterisk-1/commit/fe8b7f31db687f8b9992864b82c93d22833019c7
- https://github.com/kaoru6/asterisk/commit/1fe14f38dd43dc894d21f85762b51208ba5c8acb
- https://github.com/lyx2014/Asterisk/commit/0670e43c30135044e25cca7f80e1833e2c128653